﻿using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace QiHe
{
    class GetFlag
    {

        private const string CHAR = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";

        public string  GetChart(int len)
        {

            StringBuilder str = new StringBuilder();

            while (true)
            {
                Random ra = new Random(System.Guid.NewGuid().GetHashCode());

                str.Append(CHAR[ra.Next(36)]);

               

                if (str.Length == len)
                {

                    break;

                }

            }



            return str.ToString();

        }


    }
}
